1. Field of the Invention
The present invention relates to an ink-jet apparatus. More specifically, the invention relates to an ink-jet apparatus employing an ink-jet head having a plurality of ink ejection heaters in an ink path corresponding to each ejection opening.
2. Description of the Related Art
An ink-jet apparatus has been mainly known as a printing apparatus in printers, copy machines and so forth. Among various ink-jet apparatuses, an ink-jet printing apparatus of the type utilizing thermal energy as an energy for ejecting an ink and ejecting ink by bubble utilizing the thermal energy has been spread, recently. In addition, as other applications of this type of ink-jet printing apparatus, an ink-jet textile printing apparatus for performing printing of a given pattern, picture or synthesized image and so forth on a cloth is becoming known, in the recent years.
An ink-jet head to be employed in the ink-jet printing apparatus such as those set forth above, has an electro-thermal transducing element (hereinafter also referred to as xe2x80x9cheaterxe2x80x9d) as a source of the thermal energy. In most cases, the ink-jet head is provided with one heater corresponding to one ejection opening. On the other hand, there has been known the ink-jet head employing a plurality of heaters for each ink ejection opening, in a viewpoint discussed below.
Firstly, it has been known to drive a plurality of heaters alternately or selectively for the purpose of expanding life of the ink-jet head. Secondly, a plurality of heaters are employed for widening range of variation of ink ejection amount. In the second case, by selecting the heater to be driven and/or by selecting number of heaters to be driven, the ink ejection amount is varied.
In the later case, as more concrete structure, a plurality of heaters are arranged in alignment along an ink ejecting direction in an ink path communicated with the ejection opening of the ink-jet head so that a distance between the ejection opening and the driven heater is varied by selecting the heater to be driven (namely heater to be heated) and/or by selecting number of heaters to be driven. By this, the ejection amount of the ink can be varied.
On the other hand, as other structure, there has been known the ink-jet head, in which a plurality of heaters having mutually different surface areas are arranged in the ink path to make the ink ejection amount variable by varying the heater to be driven and/or by varying number of heaters to be driven.
However, when printing is performed employing the ink-jet head having a plurality of heaters corresponding to each of the ejection openings, there should arise the following problems.
The first problem occurs in so-called preliminary ejection to be performed as a part of an ejection recovery process.
More specifically, the preliminary ejection is to perform ink ejection from the ink-jet head irrespective of printing generally at the predetermined position in the printing apparatus. By this, the ink of increased viscosity in the ink-jet head is removed to maintain good ink ejecting condition. Such preliminary ejection is generally performed upon on-set of the power supply or at a given constant time interval during printing. However, in the case where ink ejection can be done at various ejection amounts by a plurality of heaters as set forth above, it is possible that printing is performed with setting the ink ejection amount to a small ejection amount. In such printing operation, when the preliminary ejection is performed in the small ink ejection amount, the effect of the preliminary ejection can be varied depending upon the ejection amount. For instance, amount of the ink of the increased viscosity and bubble to be discharged out of the ink-jet head can become small in the case of small ink ejecting amount during the preliminary ejection. Also, it can be said that since the ejection amount and ejection speed in such mode of printing operation is small, viscosity of the ink is easily increased. Therefore, shortening the interval of the preliminary ejection may be required to lower a throughput in printing.
The second problem is related to stabilization of ink ejection amount.
In the ink-jet head of the type ejecting the ink employing the heater, when a head temperature or an ink temperature is varied, the ink ejection amount can be varied though the variation range is not significant, in general. Therefore, when the heat temperature is elevated according to progress of printing operation, a problem of variation of the image quality can be caused due to variation of the ink ejection amount. It has been previously proposed to provide a structure for stabilizing the ink ejection amount regardless of variation of the head temperature as disclosed in Japanese Patent Application Laid-open No. 31905/1993. Here, two sequential pulses are applied to the heater for one time of ink ejection for controlling the head temperature by controlling a pulse width or so forth (hereinafter, occasionally referred to as xe2x80x9cpre-heat controlxe2x80x9d) of a preceding pulse among two pulses, so that a variation of the ink ejection amount can be decreased.
Incidentally, in structure to vary the ink ejection amount in a plurality of steps by selecting heaters to be driven in the ink-jet head by employing a plurality of heaters for ejection set forth above, it is of course desirable to maintain ejection amount stable at respective settings.
Japanese Patent Application Laid-open No. 132259/1980 discloses multi-tone expression in structure employing a plurality of heaters. However, it is clear that stabilization of the ink ejecting amount cannot be realized.
The third problem is a problem in the case where pre-heating control is employed relating to stabilization of the ejection amount associated with the second problem.
For stabilization of ejection of the ink-jet head having a plurality of heaters, it is considered to employ the structure of the pre-heat control. However, there are little problems to be considered when optimal ejection amount is to be controlled at respective ink ejection amount settings, such as a relationship between the drive heater in the set ejection amount and the heater performing preheating, a relationship between the set ejecting amount and the pulse width of the pre-heat pulse and so forth.
A fourth problem relates to multi-tone printing when a plurality of heaters are employed.
Regarding a plurality of heaters, the abovementioned prior art only shows structure for making the ink ejection amount variable by selectively driving a plurality of heaters. Therefore, it is possible that good quality of image cannot be printed even when it is applied for the multi-tone printing as is.
For example, when the ejection amount is varied in a relatively wide range by employing a plurality of heaters, the ejection speed for each ejection amount is significantly varied associating therewith. In this case, so-called serial type printing apparatus, in which printing is performed with scanning the inkjet head, a depositing position of an ejected ink can be offset by variation of the ejecting speed. As a result, a problem is encountered by lowering of the image quality.
It is a first object of the present invention to provide an ink-jet printing apparatus which can perform appropriate preliminary ejection for each ejection amount mode set by a heater selectively employed among a plurality of heaters.
Another object of the present invention, associated with the first object, is to provide an ink-jet printing apparatus which can effectively perform preliminary ejection with larger ejection amount than performing the preliminary ejection with a small ejection amount, when the preliminary ejection is performed at an interval between printing operation-performed with setting the small ejection amount.
The second object of the present invention is to provide an ink-jet apparatus enabling stabilization of the ejection amount with relatively simple structure in the ink-jet apparatus with ink-jet head having a plurality of heaters corresponding to one ejection opening.
Another object of the present invention, associated with the second object, is to provide an ink-jet apparatus, in which ejection amount is reduced in comparison with the case where pulse is applied to all of the heaters simultaneously by shifting a pulse charging timing for respective of plurality of heaters in such manner that reduction amount becomes greater by increasing the shifting amount, and in which shifting period can be varied depending upon information relating to an ink temperature of the inkjet head so as to stabilize the ejection amount, for instance, even if the ejection amount is increased due to elevating of the ink temperature, the increasing of the ink ejection amount can be suppressed by increasing the shifting period.
The third object of the present invention is to provide an ink-jet apparatus which can perform stable ejection amount control with respect to a plurality of set ejection amounts.
Associating with the above-mentioned third object, another object of the present invention is to provide an ink-jet apparatus which enables control of driving per combination of the heaters set to be driven among a plurality of heaters and which enables control of pre-pulse to be applied for stabilization of the ejection amount per combination.
The fourth object of the present invention is to provide an ink-jet apparatus which can constantly print good image even when tone printing and so forth is performed by varying the ejection amount.
Associating with the fourth object, another object of the present invention is to provide an ink-jet apparatus and ink-jet printing method which can perform printing in various modes by combination of ejection openings and ejection amount.
In a first aspect of the present invention, there is provided an ink-jet apparatus employing an ink-jet head capable of ejecting an ink in variable of an ejection amount in a plurality of steps and performing printing by ejecting an ink from the ink-jet head toward a printing medium, comprising:
printing means for performing printing operation in a predetermined ink ejection amount among the plurality of steps of ink ejection amounts in the inkjet head; and
preliminary ejection means for performing ink ejection not associated with printing, from the ink jet head, at an ejection amount greater than the predetermined ink ejection amount among the plurality of steps of ink ejection amounts.
In a second aspect of the present invention, there is provided an ink-jet apparatus employing an ink-jet head having a plurality of energy generating elements corresponding to one ejection opening and performing printing by ejecting an ink to a printing medium utilizing the energy generated by the energy generating elements, comprising:
printing means for performing printing operation in a plurality of ink ejection amount modes established by combination of an energy generating element to be used among the plurality of energy generating elements; and
preliminary ejection means for performing ink ejection not associated with printing, from the inkjet head used for printing operation, while the printing operation is performed in one of the plurality of ejection amount modes, the ink ejection by the preliminary means being performed in the ejection amount mode having ejection amount greater than or equal to the ejection amount of the ejection amount mode employed in the printing operation.
In a third aspect of the present invention, there is provided an ink-jet apparatus employing an ink-jet head having a plurality of energy generating elements corresponding to one ejection opening and performing printing by ejecting an ink to a printing medium utilizing the energy generated by the energy generating elements, comprising:
printing means for performing printing operation in a plurality of ink ejection amount modes established by combination of an energy generating element to be used among the plurality of energy generating elements; and
preliminary ejection executing means having preliminary ejection modes respectively corresponding to the plurality of ejection amount modes.
In a fourth aspect of the present invention, there is provided an ink-jet apparatus employing an ink-jet head having a plurality of heaters corresponding to one ejection opening and performing printing by ejecting an ink from the ink-jet head to a printing medium, comprising:
driving means for applying respective pulses to the plurality of heaters for bubbling the ink for ejecting the ink through the one ejection opening, the driving means being capable of mutually shifting timings of bubbling at respective of the plurality of heaters on a basis of information relating to an ink temperature of the ink-jet head.
In a fifth aspect of the present invention, there is provided an ejection amount controlling method in an ink-jet apparatus employing an ink ejecting portion having a plurality of heaters corresponding to one ejection opening and ejecting ink from the ink ejecting portion to a printing medium, the method comprising the steps of:
adjusting an ink ejection amount by mutually shifting bubbling timing at respective of the plurality of heaters upon application of respective pulses to the plurality of heaters for causing bubbling of ink to eject ink through the ink ejection opening.
In a sixth aspect of the present invention, there is provided an ejection amount stabilizing method in an ink-jet apparatus employing an ink ejecting portion having a plurality of heaters corresponding to one ejection opening and ejecting ink from the ink ejecting portion to a printing medium, the method comprising the step of:
stabilizing an ink ejection amount by mutually shifting bubbling timing at respective of the plurality of heaters upon application of respective pulses to the plurality of heaters for causing bubbling of ink to eject ink through the ink ejection opening so as to adjust the ink ejection amount.
In a seventh aspect of the present invention, there is provided an ink jet apparatus employing an ink-jet head having a plurality of heaters corresponding to one ejection opening, and ejecting ink from the ink-jet head to a printing medium, comprising:
head driving means for applying a preceding pulse which does not cause ejection and a subsequent pulse following the preceding pulse to generate a bubble for ejecting the ink;
ejection amount mode setting means for setting an ejection amount mode by selecting heater to be applied to the subsequent pulse among the plurality of heaters; and
pre-pulse control means for controlling application of the preceding pulse through the head driving means in respective ejection amount modes set by the ejection amount mode setting means, on a basis of information relating to an ink temperature of the ink-jet head.
In an eighth aspect of the present invention, there is provided an ink-jet apparatus employing an ink-jet head arranged first and second heaters corresponding to one ejection opening and ejecting an ink droplet of a selected one of a plurality of ejection amounts by generating bubble by driving the first and second heaters in combination, comprising:
driving means for driving the first and second heaters with a pre-heat pulse in advance of driving with a main heating pulse.
In a ninth aspect of the present invention, there is provided an ink-jet apparatus employing an ink-jet head arranged a plurality of mutually different heaters corresponding to one ejection opening and ejecting ink droplet of a plurality of mutually different ejection amounts by driving the plurality of heaters in combination to generate a bubble, comprising:
a table used for driving the heaters in the combination corresponding to respective combinations of the plurality of heaters.
In a tenth aspect of the present invention, there is provided an ink-jet apparatus employing an ink-jet head arranged a plurality of heaters corresponding to one ejection opening and ejecting an ink from the ink jet head to a printing medium, comprising:
setting means for setting presence or absence in heater driving irrespective of ejection data respective heaters of the plurality of heaters; and
ejection data setting means for establishing correspondence between ejection data and the ejection openings to perform ink ejection on a basis of the ejection data, depending upon combination of presence or absence of driven heaters set by the setting means.
In an eleventh aspect of the present invention, there is provided an ink-jet apparatus for performing printing employing an ink-jet head having ejection openings which can sequentially differentiate a size of ink droplet among a plurality of sizes per in each scanning cycle or per every number of scanning cycles, comprising:
means for driving the ink-jet head with relatively shifting the ink-jet head relative to the printing medium so that a plurality of different sizes of ink droplets are ejected so as to form a plurality of different sizes of dots which are complementarily disposed relative to each other.
In a twelfth aspect of the present invention, there is provided an ink-jet apparatus for performing printing employing an ink-jet head having ejection openings which can sequentially differentiate a size of ink droplet among a plurality of sizes per in each scanning cycle or per every number of scanning cycles, wherein:
ejection timing is differentiated depending upon the size of the ink droplet.
In a thirteenth aspect of the present invention, there is provided an ink-jet apparatus having an ink jet head capable of ejecting two mutually different sizes of ink droplets and capable of reciprocal printing, comprising:
first mode executing means for performing printing with a large ink droplet in one of forward and reverse printing directions;
second mode executing means for performing printing with a small ink droplet in the other of the forward and reverse printing directions; and
switching means for switching the first and second modes.
In a fourteenth aspect of the present invention, there is provided an ink-jet apparatus having an ink jet head capable of ejecting two mutually different sizes of ink droplets, comprising:
means for varying ejection timing of the ink droplet depending upon the size of the ink droplet or combination of heaters to be driven.
In a fifteenth aspect of the present invention, there is provided an ink-jet apparatus employing an ink-jet head, in which a plurality of ejection openings are arranged in a form of array, and performing printing of a density of 1/N with ejection opening group of 1/N (Nxe2x89xa72) of ejection opening array, comprising:
printing executing means for executing ejection mode depending upon the density.
In a sixteenth aspect of the present invention, there is provided an ink-jet apparatus employing ink ejecting portion having a plurality of heaters corresponding to one ejection opening and ejecting ink from the ink ejecting portion to a printing medium, comprising:
driving means for driving the plurality of heaters with varying combination of the heaters to be driven and/or varying driving energy to be applied to the heaters to be driven.
In a seventeenth aspect of the present invention, there is provided an ink-jet apparatus employing an ink-jet head capable of ejecting an ink in variable of an ejection amount in a plurality of steps and performing printing by ejecting an ink from the inkjet head toward a printing medium, comprising:
preliminary ejection means for performing preliminary ejection operation with a large ejection amount and preliminary-ejection operation with a small ejection amount; and
preliminary ejection interval setting means for setting an interval between preliminary ejection operations with the small ejection amount shorter than an interval between preliminary ejection operations with the large ejection amount.
In an eighteenth aspect of the present invention, there is provided a method for performing a preliminary ejection not associated with printing from an ink-jet head capable of ejecting an ink in variable of an ejection amount in a plurality of steps, comprising the steps of:
performing preliminary ejection operation with a large ejection amount;
performing preliminary ejection operation with a small ejection amount; and
setting an interval between preliminary ejection operations with the small ejection amount shorter than an interval between preliminary ejection operations with the large ejection amount.